Heat dissipation is a major issue of light emitting diodes applied in illumination lamps, and aluminum-substrate printed circuits are generally used as a solution to overcome the heat dissipation problem of the light emitting diodes, and thus the aluminum-substrate printed circuits gradually replace the materials of conventional printed circuit boards (such as the FR4 fiberglass boards). However, the application of the aluminum substrates creates another problem. When a power line of the lamps is soldered onto the aluminum substrate, the heat energy provided for the melting and soldering processes will be conducted through the aluminum substrate quickly, thus making the soldering process uneasy. A present solution is to solder a connector onto the aluminum substrate by a surface mount technology (SMT) method, and then insert and connect the power line to the connector. This method incurs an additional cost of the connector, and also forms shadows in the light source since the connector has a larger volume than the light emitting diode.